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1160                          Appendix VI.

sensitive regulation ensues, permitting gas -engines to be used for
the exacting requirements of electric light generation.

Better-shaped clearance spaces, as indicated by the sections in
Fig. 1023, have reduced the fluid resistance, which was considerable
in large engines when drawing air on non-firing strokes. Nothing


but good design in pipes and clearance can decrease this. In Fig.
1024 are two indicator diagrams taken with a light indicator spring,
so as to discover the area of the bottom loop : A during the firing


FAjq. 102%.      Battom, Looj^

cycle and B when drawing air. The loop area represents the
deduction to be made on account of fluid resistance from the rest
of the diagram area, its value being about jf per ?cent at A, and,
7 J- per cent at B. -